Women are more susceptible to developing Alzheimer’s disease (AD) compared to men, but the nature of this difference remains unclear. Disrupted sleep has long been identified as a symptom of AD; however, research now suggests that sleep plays a causal role in AD progression. Studies in aging primates can provide insight into the relationship between AD and sleep as well as the sex difference in AD susceptibility. Common marmosets (Callithrix jacchus) are uniquely suited for aging studies due to their naturally short lifespan and consolidated sleep patterns. We hypothesized that females would display poorer sleep quality compared to males. We recorded sleep from aging marmosets (N=20, 12 males; mean age = 7.75 years) for one to six nights (mean = 3) using activity monitors. We used general linear mixed models with a fixed effect for sex, a covariate of age and a random effect of individual. We found that males slept for a longer total time than females [F=21.9, p < 0.01]. There was no sex difference in the frequency of wake bouts, but females had longer duration [F=8.21, p < .01] and more active [F=6.04, p = 0.02] wake bouts compared to males. These preliminary results support our hypothesis that aging female marmosets have poorer sleep quality than males, which may be relevant for understanding sex differences in human susceptibility to AD.